Re: [Boost-users] [Preprocessor] Is it possible to expand recursively?

17 Jul 2011


      On 7/17/2011 1:29 PM, Edward Diener wrote:
...
On 7/17/2011 9:21 AM, TONGARI wrote:
...
Hello,
I'd like to have a macro like:
BUILD_HIERARCHY
(a,
(b,)
(c,
(d,)
(e,)
)
)
which should expand to:
struct a {};
struct b: a {};
struct c: a {};
struct d: c {};
struct e: c {};
Is this possible at all?
I have tried but with no luck, if this is impossible, please tell me so.
I think you want above:
(a,
(b)
(c,
(d)
(e)
)
)
This is a tuple with a possible second element as a seq. Each element of
your seq is a tuple with the same rule as the top tuple.
Following internal logic, perhaps with nested BOOST_PP_WHILEs, you
should be able to cycle through each tuple and nested tuple forming the
relationships you have created for your structs above. I can not
guarantee this will be doable but at least you should have some idea of
what to do from the description of what you have.
I have to correct the above. The syntax for what I described must be:

(a,
    ((b))
    ((c,
       (d)
       (e))
    )
)